Inexpensive cameras, such as single use cameras, have been provided which are pre-loaded with film in the factory, optimally in non-darkroom conditions. In those cameras, the film has been drawn from the film cassette and the unexposed film is scrolled into a roll of unexposed film on a film spool located opposite the film cassette. An exposure chamber containing a shutter and lens mechanism is located in the film path between the film spool and the film cassette. The film cassette is loaded into the film cassette receiving chamber and engaged with the film advance wheel. The film leader is pulled from the film cassette, engaged with a sprocket, passed over the exposure chamber and is attached to the take-up spool. The film is then pre-wound onto the take-up spool.
Exposed film is rewound back into the film cassette by winding the advance wheel after an exposure has been made. After all exposures have been made, the film is completely rewound into the film cassette.
To prevent error by the user, an anti-reversal pawl mechanism is provided to ensure the advance wheel can only be turned in one direction by the user. However, this mechanism additionally prevents the advance wheel from being turned in a direction necessary for pre-loading the film on the take-up spool.
Several methods are known for disengaging an anti-reversal pawl mechanism and/or metering system for film pre-loading. U.S. Pat. No. 6,016,404 to DiRisio discloses a one-time-use camera with anti-backup pawl disengaged from the film winder during film loading. In the '404 DiRisio patent, an anti-backup pawl has a fair of flexible aligned fulcrum support connections with the main body part. An actuator at a free end of the anti-backup pawl protrudes into the film take-up chamber and is movable to disengage the anti-backup pawl from the thumbwheel in response to the film spool being received in the film take-up chamber such that the film spool is moved against the actuator. When the rotation tool is separated from the film spool the anti-backup pawl pivots to engage the pawl end with any of the teeth on the underside of the film winding thumbwheel and the actuator displaces the film spool from the film unwinding position in the film take-up chamber to a film winding position in the chamber. Similarly, U.S. Pat. No. 6,049,675 to DiRisio and Lawther discloses a one-time-use camera with anti-backup pawl engaging film winder responsive to film loading. In the '675 DiRisio patent the inherently flexible anti-backup pawl is a cantilever having a support end integrally connected with the main body part within a top hole in the main body part. The anti-backup pawl is inherently biased to urge a pawl end out of engagement with respective teeth on the underside of the film winding thumbwheel to allow unwinding rotation of the thumbwheel clockwise. An actuator proximate the support end of the anti-backup pawl protrudes into the film take-up chamber. When the actuator is pushed towards the top hole, the anti-backup pawl is pivoted at the support end to engage the pawl end with any one of the teeth to prevent unwinding rotation of the thumbwheel.
U.S. Pat. No. 6,038,402 to Homing and Rydelek discloses a method of disengaging the anti-backup pawl from the film winder to permit unexposed filmstrip to be pre-wound from the film cartridge during manufacture of a one-time-use camera. The '402 Homing patent discloses a single use camera including an anti-backup pawl located in a slot of the rear cover and having an integral pair of flexible fulcrum support connections with the rear cover in the slot. A free (movable) end of the anti backup pawl is located opposite one end of the slot. Another free (movable) end, i.e. the pawl end engages the thumbwheel to prevent its unwinding rotation. The fulcrum support connections are arranged between the free end and the pawl end in the slot to permit the anti-backup pawl to be pivoted at the fulcrum support connections to move the free end inwardly of the slot and to move the pawl end outwardly of the slot, in order to disengage the pawl end from the thumbwheel. The anti-backup pawl is disengaged by manually pushing a disengaging tool against the free end of the anti-backup pawl to pivot the anti-backup pawl at the fulcrum support connections and depress the free end inwardly of the slot and move the pawl end outwardly of the slot in order to disengage the pawl end from the thumbwheel. Additionally, the '402 Horning patent discloses a prior art method of manually disengaging the anti-backup pawl from the thumbwheel involving inserting a disengaging tool behind the anti-backup pawl and prying the anti-backup pawl outwardly from the thumbwheel.
U.S. Pat. No. 6,226,457 to Boyd et al. discloses a one-time-use camera loading method. The '457 Boyd patent discloses an anti-backup subsystem mounted on the camera frame assembly and having a first mechanical member biased into a disengaged position. A main portion of the filmstrip is then wound, in a pre-wind direction, from the film cartridge to a film supply chamber of the camera from assembly. Following the winding, the first mechanical member is biased into an engaged position, in which the anti-backup system precludes winding of the filmstrip in the pre-wind direction. The first mechanical member can be biased by applying a label to a casing of the camera.
What is needed is a simple system and method for pre-loading a camera. What is further needed is a special disengagement fixture used to disengage the metering system of the camera before the film pre-winding is performed. These objects, as well as others, are satisfied by the present inventions.